Non-pneumatic tire

ABSTRACT

A non-pneumatic tire includes an attachment body ( 11 ) attached to an axle, a ring member ( 14 ) including an inner rim ( 12 ) fitted onto the attachment body ( 11 ) and an outer rim ( 13 ) configured to surround the inner rim ( 12 ) from the outside in a tire radial direction, and a plurality of connecting members ( 15 ) disposed between the inner rim ( 12 ) and the outer rim ( 13 ) in a tire circumferential direction and configured to connect the rims ( 12 ) and ( 13 ) to each other, wherein at least a portion of the ring member ( 14 ) and the plurality of connecting members ( 15 ) are integrally formed of a synthetic resin material having a bending modulus of elasticity at −20° C. obtained through a 3-point bending test that is two times or less a bending modulus of elasticity at 60° C. obtained through the 3-point bending test pursuant to ISO 178.

TECHNICAL FIELD

The present invention relates to a non-pneumatic tire in whichpressurized air need not be filled upon use.

This is a National Stage of International Application No.PCT/JP2013/083211 filed Dec. 11, 2013, claiming priority based onJapanese Patent Application No. 2012-282664, filed Dec. 26, 2012, thecontents of all of which are incorporated herein by reference.

BACKGROUND ART

In a pneumatic tire of the related art that is filled with pressurizedair and used, occurrence of a blowout is a structurally unavoidableproblem.

In order to solve this problem, in recent years, for example, asdisclosed in the following Patent Document 1, a non-pneumatic tireincluding an attachment body attached to an axle, a ring-shaped bodyconfigured to surround the attachment body from the outside in a tireradial direction, and a plurality of connecting members disposed betweenthe attachment body and the ring-shaped body in a tire circumferentialdirection is proposed.

DOCUMENT OF RELATED ART Patent Document

-   [Patent Document 1] Japanese Unexamined Patent Application, First    Publication No. 2011-156905

SUMMARY OF INVENTION Technical Problem

However, in the non-pneumatic tire of the related art, upon assemblythereof, both end sections of each of a plurality of connecting membersshould be connected to the ring-shaped body and the attachment body,which not only increases manufacturing time, but also interferes withattempts to decrease weight.

In addition, variations in temperature of the non-pneumatic tire shouldbe investigated more.

In consideration of the above-mentioned circumstances, the presentinvention is directed to provide a non-pneumatic tire capable of easyassembly, suppression of an increase in weight, and stabilization ofride comfort characteristics.

Solution to Problem

A non-pneumatic tire of the present invention includes an attachmentbody attached to an axle; a ring member including an inner rim fittedonto the attachment body and an outer rim configured to surround theinner rim from the outside in a tire radial direction; and a pluralityof connecting members disposed between the inner rim and the outer rimin a tire circumferential direction and configured to connect the rimsto each other, wherein at least a portion of the ring member and theplurality of connecting members are integrally formed of a syntheticresin material having a bending modulus of elasticity at −20° C.obtained through a 3-point bending test that is two times or less abending modulus of elasticity at 60° C. obtained through the 3-pointbending test pursuant to ISO 178.

In the present invention, since at least the portion of the ring memberand the plurality of connecting members are integrally formed, when thenon-pneumatic tire is assembled, even if both end sections of theplurality of connecting members are not connected to the inner rim andthe outer rim, it is sufficient that the case body formed by integrallyforming at least the portion of the ring member and the plurality ofconnecting members be mounted on the attachment body, and thusmanufacturing time can be reduced.

In addition, since at least the portion of the ring member and theplurality of connecting members are integrally formed, for example, anincrease in weight can be suppressed in comparison with the case inwhich both end sections of the connecting members are connected to theinner rim and the outer rim using a fastening member or the like.

In particular, since the bending modulus of elasticity of the syntheticresin material at −20° C. obtained through the 3-point bending test istwo times or less the bending modulus of elasticity at 60° C. obtainedthrough the 3-point bending test, a variation in hardness of thenon-pneumatic tire according to a variation in temperature can besuppressed. For this reason, for example, regardless of a variation inambient temperature, an increase in temperature due to repeateddeformation of the connecting member or the like during traveling, orthe like, good ride comfort characteristics can be stably exhibited.

Here, the synthetic resin material may have a bending modulus ofelasticity at 23° C. obtained through the 3-point bending test of 300MPa or more.

In this case, since the bending modulus of elasticity of the syntheticresin material integrally forming at least the portion of the ringmember and the plurality of connecting members at 23° C. obtainedthrough the 3-point bending test is within the above-mentioned range,necessary and sufficient strength for the non-pneumatic tire can bereliably provided.

In addition, when the bending modulus of elasticity of the syntheticresin material at 23° C. obtained through the 3-point bending test is12000 MPa or less, good ride comfort characteristics can be provided.

Here, the connecting members may include first elastic connecting platesand second elastic connecting plates configured to connect the rims toeach other, one end sections of the first elastic connecting platesconnected to the outer rim may be disposed closer to one side in thetire circumferential direction than the other end sections connected tothe inner rim, one end sections of the second elastic connecting platesconnected to the outer rim may be disposed closer to the other side inthe tire circumferential direction than the other end sections connectedto the inner rim, the plurality of first elastic connecting plates maybe disposed in the tire circumferential direction at one positions inthe tire width direction, and the plurality of second elastic connectingplates may be disposed in the tire circumferential direction at otherpositions in the tire width direction different from the one positionsin the tire width direction.

In this case, since the plurality of first elastic connecting plates aredisposed in the tire circumferential direction at the one positions inthe tire width direction, and the plurality of second elastic connectingplates are disposed in the tire circumferential direction at the otherpositions in the tire width direction, interference between theconnecting members neighboring in the tire circumferential direction canbe suppressed, and restriction on the number disposed can be suppressed.

In addition, since one end sections of the first elastic connectingplates connected to the outer rim are disposed closer to one side in thetire circumferential direction than the other end sections connected tothe inner rim and one end sections of the second elastic connectingplates connected to the outer rim are disposed closer to the other sidein the tire circumferential direction than the other end sectionsconnected to the inner rim, when an external force is applied to thenon-pneumatic tire, the first elastic connecting plates and the secondelastic connecting plates can be easily elastically deformed, and goodride comfort characteristics can be obtained by providing flexibility inthe non-pneumatic tire.

In addition, the ring member may be divided into one split ring memberdisposed at one side in the tire width direction and another split ringmember disposed at the other side in the tire width direction, the onesplit ring member may be integrally formed with the first elasticconnecting plates, and the other split ring member may be integrallyformed with the second elastic connecting plates.

In this case, in the first split case body in which the one split ringmember and the first elastic connecting plates are integrally formed andthe second split case body in which the other split ring member and thesecond elastic connecting plates are integrally formed, only theplurality of first elastic connecting plates or the plurality of secondelastic connecting plates extending in a certain direction are disposedbetween the outer rim and the inner rim when the tire is seen in theside view of the tire from the tire width direction, and the othersextending in another direction are not disposed therebetween.

For this reason, when the ring member and the connecting members areformed, first, the non-pneumatic tire can be easily and reliably formedin comparison with the case in which the case body having a complexstructure is formed as all of the ring member and the connecting membersare integrally formed by forming the first and second split case bodiesthat can be simply and easily formed.

Further, the one split ring member and the first elastic connectingplates, and the other split ring member and the second elasticconnecting plates, may be integrally formed through injection molding.

In this case, since the first split case body and the second split casebody are integrally formed through injection molding, the non-pneumatictire can be more easily formed.

However, as described above, in each of the split case bodies, sinceonly one of the groups of elastic connecting plates is disposed betweenthe outer rim and the inner rim, when the split case bodies areintegrally formed through injection molding, the molten resin can easilyarrive at corners in a mold, a structure of the mold can be suppressedfrom being complicated, and the non-pneumatic tire can be more easilyand reliably formed.

In addition, one end sections of a first elastic connecting plate and asecond elastic connecting plate of one of the connecting members may bedisposed at different positions in the tire width direction andconnected at the same position in the tire circumferential direction inan inner circumferential surface of the outer rim, and the connectingmember may extend in the tire radial direction when the tire is seen ina side view of the tire from the tire width direction, and may beline-symmetrically formed with respect to an imaginary line passingthrough the one end sections.

In this case, since the connecting member is line-symmetrically formedwith respect to the imaginary line when seen in the side view of thetire, occurrence of a difference between a spring constant along oneside in the tire circumferential direction of the non-pneumatic tire anda spring constant along the other side can be suppressed, and goodcontrollability can be provided.

Effects of the Invention

According to the present invention, the non-pneumatic tire can be easilyassembled, and an increase in weight thereof can be suppressed tostabilize ride comfort characteristics.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partially exploded schematic perspective view of anon-pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a side view of the non-pneumatic tire shown in FIG. 1 whenseen from one side in a tire width direction.

FIG. 3 is a plan view of a first split case body of the non-pneumatictire shown in FIG. 1, in which a split ring member of one side and afirst elastic connecting plate are integrally formed, when seen from oneside in the tire width direction, or a plan view of a second split casebody in which a split ring member of the other side and a second elasticconnecting plate are integrally formed, when seen from the other side inthe tire width direction.

FIG. 4 is an enlarged view showing a major portion of FIG. 2.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a non-pneumatic tire according to thepresent invention will be described with reference to FIGS. 1 to 4.

A non-pneumatic tire 1 includes an attachment body 11 attached to anaxle (not shown), a ring member 14 including an inner rim 12 fitted ontothe attachment body 11 and an outer rim 13 configured to surround theinner rim 12 from the outside in a tire radial direction, a plurality ofconnecting members 15 disposed between the inner rim 12 and the outerrim 13 in a tire circumferential direction and configured to connect therims 12 and 13 to each other in a relatively elastically displaceablemanner, and a tread member 16 disposed at an outer circumferentialsurface side of the outer rim 13 throughout the entire circumference.

Here, the attachment body 11, the inner rim 12, the outer rim 13, andthe tread member 16 are disposed on the same axis as a common axis.Hereinafter, the common axis is referred to as an axis O, a directionalong the axis O is referred to as a tire width direction H, a directionperpendicular to the axis O is referred to as a tire radial direction,and a direction around the axis O is referred to as a tirecircumferential direction. Further, the attachment body 11, the innerrim 12, the outer rim 13, and the tread member 16 are disposed such thatcentral sections in the tire width direction H coincide with each other.

In the ring member 14, the outer rim 13 has a larger size in the tirewidth direction H, i.e., a larger width, than the inner rim 12. Inaddition, a plurality of ridge sections 12 a protruding inward in thetire radial direction and extending throughout the entire length in thetire width direction H are disposed at an inner circumferential surfaceof the inner rim 12 at intervals in the tire circumferential direction.

As shown in FIGS. 1 and 2, the attachment body 11 includes a mountingcylindrical section 17 on which a front end section of the axle ismounted, an outer ring section 18 configured to surround the mountingcylindrical section 17 from the outside in the tire radial direction,and a plurality of ribs 19 configured to connect the mountingcylindrical section 17 and the outer ring section 18.

The mounting cylindrical section 17, the outer ring section 18, and theribs 19 are integrally formed of a metal material such as an aluminumalloy or the like. The mounting cylindrical section 17 and the outerring section 18 are formed in a cylindrical shape and disposed on thesame axis as the axis O. The plurality of ribs 19 are disposed at equalintervals in the circumferential direction.

A plurality of key groove sections 18 a concaved inward in the tireradial direction and extending in the tire width direction H are formedat an outer circumferential surface of the outer ring section 18 atintervals in the tire circumferential direction. In the outercircumferential surface of the outer ring section 18, the key groovesections 18 a are opened at only one side of both ends in the tire widthdirection H and closed at the other side. The ridge sections 12 a of theinner rim 12 in the ring member 14 are fitted into the key groovesections 18 a.

Further, in wall surfaces configured to form the key groove sections 18a, a pair of side wall surfaces opposite to each other in the tirecircumferential direction are perpendicular to a bottom wall surface. Inaddition, in outer surfaces of the ridge sections 12 a, the pair of sidewall surfaces standing upward from the inner circumferential surface ofthe inner rim 12 are perpendicular to a top wall surface directed inwardin the tire radial direction. Sizes in the tire circumferentialdirection of the ridge sections 12 a and the key groove sections 18 aare equal to each other.

Here, in an edge of one side in the tire width direction H of the outerring section 18, concave sections 18 b concaved toward the other side inthe tire width direction H and into which plate members 28 are fittedare formed at positions corresponding to the key groove sections 18 a.Through-holes are formed in the plate members 28, and in the wallsurfaces that form the concave sections 18 b, female screw sections incommunication with the through-holes of the plate members 28 fitted intothe concave sections 18 b are formed in the wall surface facing the oneside in the tire width direction H. Further, the plurality of femalescrew sections and the plurality of through-holes are formed atintervals in the tire circumferential direction.

Then, the ring member 14 is fixed to the attachment body 11 by boltsthreaded into the female screw sections through the through-holes of theplate members 28 fitted into the concave sections 18 b in a state inwhich the inner rim 12 is fitted onto the attachment body 11 from theoutside and the ridge sections 12 a are fitted into the key groovesections 18 a. In this state, the ridge sections 12 a are sandwichedbetween the plate members 28 and the other end wall surfaces of the wallsurfaces forming the concave sections 18 b disposed at the other end inthe tire width direction H and facing the one side in the tire widthdirection H.

Further, a plurality of hole arrays 18 c, in each of which a pluralityof weight-reducing holes passing in the tire radial direction aredisposed at intervals in the tire width direction H, are formed at aportion of the outer ring section 18 disposed between the key groovesections 18 a neighboring in the tire circumferential direction atintervals in the tire circumferential direction. In addition,weight-reducing holes 19 a passing in the tire width direction H arealso formed in the ribs 19.

The tread member 16 is formed in a cylindrical shape, and integrallycovers the outer circumferential surface side of the outer rim 13 of thering member 14 throughout the entire region. The tread member 16 isformed of, for example, natural rubber or/and vulcanized rubber in whicha rubber composition is vulcanized, a thermoplastic material, or thelike. For example, a thermoplastic elastomer, a thermoplastic resin, orthe like is provided as the thermoplastic material. For example, anamide-based thermoplastic elastomer (TPA), an ester-based thermoplasticelastomer (TPC), an olefin-based thermoplastic elastomer (TPO), astyrene-based thermoplastic elastomer (TPS), a urethane-basedthermoplastic elastomer (TPU), a thermoplastic rubber cross-linked body(TPV), or another thermoplastic elastomer (TPZ) or the like, defined byJapanese Industrial Standards JIS K6418, is provided as thethermoplastic elastomer. For example, a urethane resin, an olefin resin,a polyvinyl chloride resin, a polyamide resin, or the like, is providedas the thermoplastic resin. Further, in view of an abrasion resistanceproperty, the tread member 16 may be formed of the vulcanized rubber.

The connecting members 15 include first elastic connecting plates 21 andsecond elastic connecting plates 22 configured to connect the inner rim12 and the outer rim 13 of the ring member 14.

The plurality of (in the example shown, 60) connecting members 15 areinstalled in the tire circumferential direction such that the pluralityof first elastic connecting plates 21 are disposed in the tirecircumferential direction at one predetermined positions in the tirewidth direction H, and the plurality of second elastic connecting plates22 are disposed in the tire circumferential direction at other positionsin the tire width direction H different from the one predeterminedpositions in the tire width direction H.

That is, the plurality of first elastic connecting plates 21 aredisposed in the tire circumferential direction at the same positions asin the tire width direction H, and the plurality of second elasticconnecting plates 22 are disposed in the tire circumferential directionat predetermined positions in the same tire width direction H spacedapart from the first elastic connecting plates 21 in the tire widthdirection H.

Further, the plurality of connecting members 15 are disposed atpositions rotationally symmetrical with respect to the axis O betweenthe inner rim 12 and the outer rim 13 of the ring member 14. Inaddition, all of the connecting members 15 have the same shape and thesame size. Further, widths of the connecting members 15 are smaller thana width of the outer rim 13.

The first elastic connecting plates 21 neighboring in the tirecircumferential direction do not come in contact with each other, andthe second elastic connecting plates 22 neighboring in the tirecircumferential direction do not come in contact with each other either.Further, the first elastic connecting plates 21 and the second elasticconnecting plates 22 neighboring in the tire width direction H do notcome in contact with each other either.

Further, the first elastic connecting plates 21 and the second elasticconnecting plates 22 have the same widths. In addition, the firstelastic connecting plates 21 and the second elastic connecting plates 22also have the same thicknesses.

Here, in the first elastic connecting plates 21, one end sections 21 aconnected to the outer rim 13 are disposed closer to one side in thetire circumferential direction than other end sections 21 b connected tothe inner rim 12, and in the second elastic connecting plates 22, oneend sections 22 a connected to the outer rim 13 are disposed closer tothe other side in the tire circumferential direction than the other endsections 22 b connected to the inner rim 12.

In addition, the one end sections 21 a and 22 a of the first elasticconnecting plates 21 and the second elastic connecting plates 22 of theone connecting members 15 are disposed at different positions in thetire width direction H and connected at the same positions in the tirecircumferential direction in the inner circumferential surface of theouter rim 13.

In the example shown, in the first elastic connecting plates 21 and thesecond elastic connecting plates 22, a plurality of curved sections 21 dto 21 f and 22 d to 22 f curved in the tire circumferential directionare formed at intermediate portions 21 c and 22 c disposed between theone end sections 21 a and 22 a and the other end sections 21 b and 22 bin a direction in which the connecting plates 21 and 22 extend when thetire 1 is seen from the tire width direction H in a side view of thetire. In the plurality of curved sections 21 d to 21 f and 22 d to 22 fof all of the connecting plates 21 and 22, curve directions of thecurved sections 21 d to 21 f and 22 d to 22 f neighboring in theabove-mentioned extending direction are opposite to each other.

The plurality of curved sections 21 d to 21 f formed at the firstelastic connecting plates 21 have the first curved sections 21 d curvedto protrude toward the other side in the tire circumferential direction,the second curved sections 21 e disposed between the first curvedsections 21 d and the one end sections 21 a and curved to protrudetoward the one side in the tire circumferential direction, and the thirdcurved sections 21 f disposed between the first curved sections 21 d andthe other end sections 21 b and curved to protrude toward the one sidein the tire circumferential direction.

The plurality of curved sections 22 d to 22 f formed at the secondelastic connecting plates 22 have the first curved sections 22 d curvedto protrude toward the one side in the tire circumferential direction,the second curved sections 22 e disposed between the first curvedsections 22 d and the one end sections 22 a and curved to protrudetoward the other side in the tire circumferential direction, and thethird curved sections 22 f disposed between the first curved sections 22d and the other end sections 22 b and curved to protrude toward theother side in the tire circumferential direction.

In the example shown, the first curved sections 21 d and 22 d havelarger radii of curvature when seen from the side view of the tire thanthe second curved sections 21 e and 22 e and the third curved sections21 f and 22 f Further, the first curved sections 21 d and 22 d aredisposed at a central section in the extending direction of the firstelastic connecting plates 21 and the second elastic connecting plates22.

Further, the lengths of all of the elastic connecting plates 21 and 22are equal to one another, and, as shown in FIG. 4, the other endsections 21 b and 22 b of all of the elastic connecting plates 21 and 22are connected to positions spaced the same angle (for example, 20° ormore to 135° or less) from positions in the outer circumferentialsurface of the inner rim 12 opposite to the one end sections 21 a and 22a in the tire radial direction at one side and the other side in thetire circumferential direction about the axis O when seen in the sideview of the tire. In addition, the first curved sections 21 d and 22 d,the second curved sections 21 e and 22 e, and the third curved sections21 f and 22 f of the first elastic connecting plates 21 and the secondelastic connecting plates 22 protrude to oppose each other in the tirecircumferential direction and have the same sizes.

Accordingly, as shown in FIG. 4, shapes of the connecting members 15when seen in the side view of the tire extend in the tire radialdirection, and are linearly symmetrical with respect to an imaginaryline L passing through the one end sections 21 a and 22 a of all of theconnecting plates 21 and 22.

In addition, in all of the elastic connecting plates 21 and 22, one endside portions extending from the central section to the one end sections21 a and 22 a in the above-mentioned extending direction have largerthicknesses than the other end side portions extending from the centralsection to the other end sections 21 b and 22 b. Accordingly, strengthof the one end side portions to which a large load in the first andsecond elastic connecting plates 21 and 22 is easily applied can beincreased while suppressing an increase in weight of the connectingmembers 15 and securing flexibility of the connecting members 15.Further, the one end side portions smoothly continue to the other endside portions with no step difference.

In the embodiment, the ring member 14 and the plurality of connectingmembers 15 are integrally formed of a synthetic resin material. Abending modulus of elasticity of the synthetic resin material at −20° C.obtained through a 3-point bending test pursuant to ISO 178 is 2.0 timesor less a bending modulus of elasticity at 60° C. obtained through the3-point bending test. Further, a bending modulus of elasticity of thesynthetic resin material at −20° C. obtained through the 3-point bendingtest is larger than a bending modulus of elasticity at 60° C. obtainedthrough the 3-point bending test. In addition, a bending modulus ofelasticity of the synthetic resin material at 23° C. obtained throughthe 3-point bending test is 300 MPa or more. Further, a bending modulusof elasticity of the synthetic resin material at 23° C. obtained throughthe 3-point bending test is 12000 MPa or less. In addition, thesynthetic resin material may be only one kind of resin material, amixture including two or more kinds of resin materials, or a mixtureincluding one or more kinds of resin material and one or more kinds ofelastomers, and further, for example, may include additives such as anantioxidant, a plasticizer, a filler, a fiber, a pigment, or the like.

Further, in the embodiment, as shown in FIG. 1, the ring member 14 isdivided into one split ring member 23 disposed at one side in the tirewidth direction H and another split ring member 24 disposed at the otherside in the tire width direction H. Further, in the shown example, thering member 14 is divided at a central section in the tire widthdirection H.

Then, the one split ring member 23 is integrally formed with the firstelastic connecting plates 21, and the other split ring member 24 isintegrally formed with the second elastic connecting plates 22.

Further, in the embodiment, the one split ring member 23 and the firstelastic connecting plates 21, and the other split ring member 24 and thesecond elastic connecting plates 22 are integrally formed throughinjection molding.

Hereinafter, a member obtained by integrally forming the one split ringmember 23 and the first elastic connecting plates 21 is referred to as afirst split case body 31, and a member obtained by integrally formingthe other split ring member 24 and the second elastic connecting plates22 is referred to as a second split case body 32.

Here, the injection molding may be a general method of simultaneouslyforming the entire each of the first and second split case bodies 31 and32, and in the first and second split case bodies 31 and 32, one of theone and the other split ring members 23 and 24 and the first and secondelastic connecting plates 21 and 22 may be an insert product, and theother may be an insert molding product formed through injection molding,or so-called two color formation, or the like.

In addition, in the first and second split case bodies 31 and 32, theone and the other split ring members 23 and 24 and the first and secondelastic connecting plates 21 and 22 may be formed of differentmaterials, or may be formed of the same material.

Further, when the entire each of the first and second split case bodies31 and 32 is simultaneously injection-molded, the plurality of ridgesections 12 a formed at the inner rim 12 may be a gate portion.

In the first and second split case bodies 31 and 32, a central sectionin the tire width direction H of the first and second elastic connectingplates 21 and 22, a central section in the tire width direction H of theouter rim 13, and a central section in the tire width direction H of theinner rim 12 coincide with each other, and the inner rim 12 has asmaller width than the outer rim 13, and has the same width as the firstelastic connecting plates 21 and the second elastic connecting plates22.

Then, edges in the tire width direction H of the outer rim 13 of the onesplit ring member 23 and the outer rim 13 of the other split ring member24 are connected by, for example, welding, fusion, adhesion, or thelike. Further, among these, in the case of the welding, for example, hotplate welding or the like may be employed.

In addition, edges in the tire width direction H of the inner rim 12 ofthe one split ring member 23 and the inner rim 12 of the other splitring member 24 are separated from each other in the tire width directionH. Accordingly, generation of burrs on the inner circumferential surfaceof the inner rim 12 fitted onto the attachment body 11 from the outsideis prevented.

In addition, the first split case body 31 and the second split case body32 have the same shape and the same size as shown in FIG. 3 in a statebefore the bodies 31 and 32 are connected as described above.

Then, when connected as described above, the non-pneumatic tire 1 isobtained as the edges in the tire width direction H of the outer rims 13of the first split case body 31 and the second split case body 32 matchto be connected to each other in a state in which directions in the tirewidth direction H of both of the split case bodies 31 and 32 areopposite to each other while matching the positions in the tirecircumferential direction of the first split case body 31 and the secondsplit case body 32, such that the connecting members 15 arepoint-symmetrical to each other as described above when seen in the sideview of the tire.

As described above, since the non-pneumatic tire 1 according to theembodiment includes the first split case body 31 in which the one splitring member 23 and the first elastic connecting plates 21 are integrallyformed, and the second split case body 32 in which the other split ringmember 24 and the second elastic connecting plates 22 are integrallyformed, when the non-pneumatic tire 1 is assembled, even if not all ofthe end sections 21 a, 22 a, 21 b and 22 b of the plurality ofconnecting members 15 are connected to the inner rim 12 and the outerrim 13, since it is enough that the first and second split case bodies31 and 32 be mounted on the attachment body 11, manufacturing time canbe reduced.

In addition, since the first and second split case bodies 31 and 32 areprovided, for example, an increase in weight can be suppressed incomparison with the case in which all of the end sections 21 a, 22 a, 21b and 22 b of the connecting member 15 are connected to the inner rim 12and the outer rim 13 using a fastening member or the like.

In particular, the bending modulus of elasticity at −20° C. obtainedthrough the 3-point bending test of the synthetic resin material thatintegrally forms the ring member 14 and the plurality of connectingmembers 15 is two times or less the bending modulus of elasticity at 60°C. obtained through the 3-point bending test. For this reason, avariation in hardness of the non-pneumatic tire 1 according to avariation in temperature can be suppressed, and for example, ridecomfort characteristics can be stabilized regardless of a variation inambient temperature, an increase in temperature due to repeateddeformation of the connecting member 15 or the like during travel, andso on.

In addition, since the bending modulus of elasticity of the syntheticresin material at 23° C. obtained through the 3-point bending test isset within the above-mentioned range, necessary and sufficient strengthfor the non-pneumatic tire 1 can be reliably provided.

In addition, when the bending modulus of elasticity of the syntheticresin material at 23° C. obtained through the 3-point bending test is12000 MPa or less, good ride comfort characteristics can be provided.

Further, since the plurality of first elastic connecting plates 21 aredisposed in the tire circumferential direction at one predeterminedpositions in the tire width direction H and the plurality of secondelastic connecting plates 22 are disposed in the tire circumferentialdirection at other positions in the tire width direction H, interferencebetween the connecting members 15 neighboring in the tirecircumferential direction can be suppressed, and restriction on thenumber disposed can be suppressed.

In addition, the one end sections 21 a of the first elastic connectingplates 21 connected to the outer rim 13 are disposed closer to one sidein the tire circumferential direction than the other end sections 21 bconnected to the inner rim 12, and the one end sections 22 a of thesecond elastic connecting plates 22 connected to the outer rim 13 aredisposed closer to the other side in the tire circumferential directionthan the other end sections 22 b connected to the inner rim 12. For thisreason, when an external force is applied to the non-pneumatic tire 1,the first elastic connecting plate 21 and the second elastic connectingplate 22 can be easily elastically deformed, and flexibility can beprovided to the non-pneumatic tire 1 to secure good ride comfortcharacteristics.

Further, in the first split case body 31 and the second split case body32, either the plurality of first elastic connecting plates 21 or theplurality of second elastic connecting plates 22 which extend in acertain direction are disposed in plural between the outer rim 13 andthe inner rim 12 when seen in the side view of the tire, and the otherswhich extend in another direction are not disposed therebetween. Forthis reason, when the ring member 14 and the connecting members 15 areformed, first, by forming the first and second split case bodies 31 and32 having structures that can be simply and easily formed, all of thering member 14 and the connecting members 15 can be integrally formed.Accordingly, in comparison with the case in which the case body having acomplex structure is formed, the non-pneumatic tire 1 can be easily andreliably formed.

In addition, since the first and second split case bodies 31 and 32 areintegrally formed through injection molding, the non-pneumatic tire 1can be more easily formed.

However, as described above, in the split case bodies 31 and 32, onlyone of the groups of elastic connecting plates 21 and 22 is disposedbetween the outer rim 13 and the inner rim 12. Accordingly, when thesplit case bodies 31 and 32 are integrally formed through injectionmolding, a molten resin can easily and reliably arrive at corners in themold, and the structure of the mold can be suppressed from beingcomplicated. Accordingly, the non-pneumatic tire 1 can be more easilyand reliably formed.

In addition, since the connecting members 15 are line-symmetricallyformed with respect to the imaginary line L when seen in the side viewof the tire, occurrence of a difference between a spring constant alongone side in the tire circumferential direction of the non-pneumatic tire1 and a spring constant along the other side can be suppressed, and goodcontrollability can be provided.

Further, the technical spirit of the present invention is not limited tothe embodiment but various modifications may be made without departingfrom the spirit of the present invention.

For example, curve directions of the curved sections 21 d to 21 f in thefirst elastic connecting plates 21 and curve directions of the curvedsections 22 d to 22 f in the second elastic connecting plates 22 are notlimited to the embodiment but may be appropriately varied.

In addition, in the embodiment, a configuration in which one of thefirst elastic connecting plates 21 and the second elastic connectingplates 22 are provided in as the connecting members 15 is shown.However, instead of this, a configuration in which both of a pluralityof the first elastic connecting plates 21 and a plurality of the secondelastic connecting plates 22 are provided as the connecting members 15at different positions in the tire width direction H may be employed.

In addition, the plurality of connecting members 15 may be disposed inthe tire width direction H between the inner rim 12 and the outer rim13.

In addition, unlike the embodiment, for example, the other end sections21 b and 22 b of the first elastic connecting plates 21 and the secondelastic connecting plates 22 may be connected at opposite positions ofthe outer circumferential surface of the inner rim 12 with the axis Ointerposed therebetween in the tire radial direction. Alternatively, inthe outer circumferential surface of the inner rim 12, they may beconnected to the one end sections 21 a and 22 a of the first elasticconnecting plate 21 and the second elastic connecting plate 22 atopposite positions or the like in the tire radial direction.

In addition, unlike the embodiment, the one end sections 21 a and 22 aof all of the connecting plates 21 and 22 may be connected to the innercircumferential surface of the outer rim 13 at different positions inthe tire circumferential direction.

Further, a gap in the tire width direction H may not be provided betweenthe inner rim 12 of the one split ring member 23 and the inner rim 12 ofthe other split ring member 24.

In addition, the ring member 14 may be divided into three portions ormore in the tire width direction H, or may not be divided.

Further, only the inner rim 12 of the ring member 14 and the connectingmembers 15 may be integrally formed of the synthetic resin material, oronly the outer rim 13 of the ring member 14 and the connecting members15 may be integrally formed of the synthetic resin material.

Moreover, the components of the above-mentioned embodiment may beappropriately substituted with known components or the above-mentionedvariants may be appropriately combined without departing from the spiritof the present invention.

Next, a verification test with respect to the above-mentioned effectswas performed.

For example, as shown in Table 1, ten kinds of non-pneumatic tires inwhich the ring member 14 and the plurality of connecting members 15 wereintegrally formed of the synthetic resin material having the bendingmodulus of elasticity at −20° C. obtained through the 3-point bendingtest that was two times or less the bending modulus of elasticity at 60°C. obtained through the 3-point bending test were formed. As acomparative example, as shown in Table 2, two kinds of non-pneumatictires in which the ring member 14 and the plurality of connectingmembers 15 were integrally formed of the synthetic resin material havingthe bending modulus of elasticity at −20° C. obtained through the3-point bending test that was two times the bending modulus ofelasticity at 60° C. obtained through the 3-point bending test wereformed. The bending modulus of elasticity at 23° C. obtained through the3-point bending test of the synthetic resin material of the example andthe comparative example was 300 MPa or more.

Here, numbers in parentheses disclosed in the columns “Bending modulusof elasticity (ratio)” in Table 1 and Table 2 represent ratios of resinsunder the presumption that the size of the bending modulus of elasticityat 60° C. obtained through the 3-point bending test is 100.

Then, with respect to twelve kinds of non-pneumatic tires, under anambient temperature of 23° C., it was confirmed whether the tire brokewhen a compression force of 3000 kN was applied in the tire radialdirection or whether the tire broke when the tire was compressivelydeformed by 20 mm in the tire radial direction.

As a result, it was confirmed that none of the non-pneumatic tires ofthe examples and the comparative examples broke.

Next, the twelve kinds of non-pneumatic tires were mounted on a vehicle,and a difference in ride comfort when the vehicle traveled under anambient temperature of 23° C. and an ambient temperature of 5° C. wasestimated according to the feeling of a driver.

As a result, when the non-pneumatic tires of the example were mounted onthe vehicle, no difference in ride comfort in the different ambienttemperatures could be felt. Meanwhile, when the non-pneumatic tires ofthe comparative example were mounted on the vehicle, it was confirmedthat a difference in ride comfort was felt.

TABLE 1 Embodi- Embodi- Embodi- Embodi- Embodi- Embodi- Embodi- Embodi-Embodi- Embodi- ment 1 ment 2 ment 3 ment 4 ment 5 ment 6 ment 7 ment 8ment 9 ment 10 Kind of resin PPS PPS PPS PPS PPS PPS PPS PPS ABS PC/ABSMaker DIC Inc. DIC Inc. Poly- Toray Inc. DIC Inc. DIC Inc. DIC Inc. DICInc. Denki Mitsubishi plastic Kagaku Engineering Inc. Kogyo Inc. PlasticInc. Grade FZ2100 Z200-E5 0220A9 A900 Z200J1 Z300 Z230 Z240 MarekkaIupiron (Trademark) (Trademark) K-200 MB-2112 Bending −20° C.  3714 MPa3317 MPa 3702 MPa 2167 MPa 2442 MPa 1585 MPa 9865 MPa 12760 MPa 2033 MPa1872 MPa modulus (109) (115) (116) (130) (114) (113) (105) (106) (147)(156) of elas-  0° C. 3519 MPa 3056 MPa 3401 MPa 1959 MPa 2340 MPa 1476MPa — — 1847 MPa 1509 MPa ticity (103) (106) (107) (118) (110) (105)(134) (125) (ratio) 23° C. 3623 MPa 3141 MPa 3465 MPa 1939 MPa 2368 MPa1534 MPa 9677 MPa 12600 MPa 1439 MPa 1368 Mpa (106) (109) (109) (116)(111) (109) (103) (104) (104) (114) 40° C. — — — — — — — — 1476 MPa 1213MPa (107) (101) 60° C. 3414 MPa 2878 MPa 3193 MPa 1666 MPa 2137 MPa 1404MPa 9376 MPa 12090 MPa 1379 MPa 1203 MPa (100) (100) (100) (100) (100)(100) (100) (100) (100) (100) Tire estimation ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Ridecomfort ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯

TABLE 2 Comparative Comparative Example 1 Example 2 Kind of resin Nylon6 Nylon 66 Maker Unitika Inc. Unitika Inc. Grade AR1030 A125JBK Bendingmodulus −20° C.   1989 MPa 2012 MPa of elasticity (ratio) (463) (441) 0° C. 2165 MPa 1910 MPa (504) (419) 23° C. 1043 MPa 1736 MPa (243)(381) 40° C.  463 MPa  762 MPa (108) (167) 60° C.  429 MPa  456 MPa(100) (100) Tire estimation ◯ ◯ Ride comfort X X

INDUSTRIAL APPLICABILITY

A non-pneumatic tire can be easily assembled, and an increase in weightcan be suppressed to stabilize ride comfort characteristics.

DESCRIPTION OF REFERENCE SIGNS

-   1 non-pneumatic tire-   11 attachment body-   12 inner rim-   13 outer rim-   14 ring member-   15 connecting member-   21 first elastic connecting plate-   22 second elastic connecting plate-   21 a, 22 a one end section-   21 b, 22 b other end section-   23 one split ring member-   24 other split ring member-   H tire width direction-   L imaginary line-   O axis

The invention claimed is:
 1. A non-pneumatic tire comprising: anattachment body attached to an axle; a ring member including an innerrim fitted onto the attachment body and an outer rim configured tosurround the inner rim from the outside in a tire radial direction; anda plurality of connecting members disposed between the inner rim and theouter rim in a tire circumferential direction and configured to connectthe rims to each other, wherein at least a portion of the ring memberand the plurality of connecting members are integrally formed of asynthetic resin material having a bending modulus of elasticity at −20°C. obtained through a 3-point bending test that is two times or less abending modulus of elasticity at 60° C. obtained through the 3-pointbending test pursuant to ISO 178 (2010), wherein one end sections of theconnecting members connected to the outer rim are disposed closer to theother side in the tire circumferential direction than the other endsections connected to the inner rim, wherein the connecting memberscomprise first elastic connecting plates and second elastic connectingplates configured to connect the rims to each other, and wherein thefirst elastic connecting plates and the second elastic connecting platesneighboring in the tire circumferential direction do not come in contactwith each other.
 2. The non-pneumatic tire according to claim 1, whereina bending modulus of elasticity of the synthetic resin material at 23°C. obtained through the 3-point bending test is 300 MPa or more.
 3. Thenon-pneumatic tire according to claim 2, wherein the connecting memberscomprise first elastic connecting plates and a second elastic connectingplates configured to connect the rims to each other, one end sections ofthe first elastic connecting plates connected to the outer rim aredisposed closer to one side in the tire circumferential direction thanthe other end sections connected to the inner rim, one end sections ofthe second elastic connecting plates connected to the outer rim aredisposed closer to the other side in the tire circumferential directionthan the other end sections connected to the inner rim, and theplurality of first elastic connecting plates are disposed in the tirecircumferential direction at one positions in the tire width direction,and the plurality of second elastic connecting plates are disposed inthe tire circumferential direction at other positions in the tire widthdirection different from the one positions in the tire width direction.4. The non-pneumatic tire according to claim 3, wherein one end sectionsof a first elastic connecting plate and a second elastic connectingplate of one of the connecting members are disposed at differentpositions in the tire width direction and connected at the same positionin the tire circumferential direction in the inner circumferentialsurface of the outer rim, and the connecting member isline-symmetrically formed with respect to an imaginary line passingthrough the one end sections and extending in the tire radial directionwhen the tire is seen in the side view of the tire from the tire widthdirection.
 5. The non-pneumatic tire according to claim 1, wherein oneend sections of the first elastic connecting plates connected to theouter rim are disposed closer to one side in the tire circumferentialdirection than the other end sections connected to the inner rim, oneend sections of the second elastic connecting plates connected to theouter rim are disposed closer to the other side in the tirecircumferential direction than the other end sections connected to theinner rim, and the plurality of first elastic connecting plates aredisposed in the tire circumferential direction at one positions in thetire width direction, and the plurality of second elastic connectingplates are disposed in the tire circumferential direction at otherpositions in the tire width direction different from the one positionsin the tire width direction.
 6. The non-pneumatic tire according toclaim 5, wherein the ring member is divided into one split ring memberdisposed at one side in the tire width direction and another split ringmember disposed at the other side in the tire width direction, the onesplit ring member is integrally formed with the first elastic connectingplates, and the other split ring member is integrally formed with thesecond elastic connecting plates.
 7. The non-pneumatic tire according toclaim 6, wherein the one split ring member and the first elasticconnecting plates, and the other split ring member and the secondelastic connecting plates are integrally formed through injectionmolding.
 8. The non-pneumatic tire according to claim 7, wherein one endsections of a first elastic connecting plate and a second elasticconnecting plate of one of the connecting members are disposed atdifferent positions in the tire width direction and connected at thesame position in the tire circumferential direction in the innercircumferential surface of the outer rim, and the connecting member isline-symmetrically formed with respect to an imaginary line passingthrough the one end sections and extending the tire radial directionwhen the tire is seen in the side view of the tire from the tire widthdirection.
 9. The non-pneumatic tire according to claim 6, wherein oneend sections of a first elastic connecting plate and a second elasticconnecting plate of one of the connecting members are disposed atdifferent positions in the tire width direction and connected at thesame position in the tire circumferential direction in the innercircumferential surface of the outer rim, and the connecting member isline-symmetrically formed with respect to an imaginary line passingthrough the one end sections and extending in the radial direction whenthe tire is seen in the side view of the tire from the tire widthdirection.
 10. The non-pneumatic tire according to claim 5, wherein oneend sections of a first elastic connecting plate and a second elasticconnecting plate of one of the connecting members are disposed atdifferent positions in the tire width direction and connected at thesame position in the tire circumferential direction in an innercircumferential surface of the outer rim, and the connecting memberextends in the tire radial direction when the tire is seen in a sideview of the tire from the tire width direction, and isline-symmetrically formed with respect to an imaginary line passingthrough the one end sections.